1. Field of the Invention
The present invention relates to a transformer, and more particularly, to a transformer capable of significantly reducing leakage inductance while satisfying safety standards.
2. Description of the Related Art
Various kinds of power supplies are required in various electronic devices such as a television (TV), a monitor, a personal computer (PC), an office automation (OA) device, and the like. Therefore, these electronic devices generally include power supplies converting alternating current (AC) power supplied from the outside into power having an appropriate level for individual electronic appliances.
Among power supplies, a power supply using a switching mode (for example, a switched-mode power supply (SMPS)) has mainly been used. An SMPS basically includes a switching transformer.
The switching transformer generally converts AC power of 85 to 265 V into direct current (DC) power of 3 to 30 V through high frequency oscillation at 25 to 100 KHz. Therefore, in the switching transformer, a core and a bobbin may be significantly reduced in size as compared to a general transformer converting AC power of 85 to 265 V into DC current of 3 to 30 V through frequency oscillation at 50 to 60 Hz, and low voltage and low current DC power may be stably supplied to an electronic appliance. Therefore, the switching transformer has been widely used in electronic appliances that have tended to be miniaturized.
This switching transformer should be designed to have relatively low leakage inductance in order to increase energy conversion efficiency. However, in accordance with the miniaturization of the switching transformer, it is not easy to design a switching transformer having small leakage inductance.
In addition, in the case in which a small-sized transformer, as described above, is manufactured, since a primary coil and a secondary coil are disposed to be immediately adjacent to each other, it may be difficult to satisfy safety standards (that is, those of Underwriters Laboratories (UL)) due to the arrangement thereof.